linux-kernel - Re: [PATCH] PCI: qcom-ep: Do not enable resources during probe()

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Message-ID: <20240815181557.GA53448@bhelgaas>
Date: Thu, 15 Aug 2024 13:15:57 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc: lpieralisi@...nel.org, kw@...ux.com, robh@...nel.org,
	bhelgaas@...gle.com, linux-arm-msm@...r.kernel.org,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: qcom-ep: Do not enable resources during probe()

On Sat, Jul 27, 2024 at 02:36:04PM +0530, Manivannan Sadhasivam wrote:
> Starting from commit 869bc5253406 ("PCI: dwc: ep: Fix DBI access failure
> for drivers requiring refclk from host"), all the hardware register access
> (like DBI) were moved to dw_pcie_ep_init_registers() which gets called only
> in qcom_pcie_perst_deassert() i.e., only after the endpoint received refclk
> from host.
> 
> So there is no need to enable the endpoint resources (like clk, regulators,
> PHY) during probe(). Hence, remove the call to qcom_pcie_enable_resources()
> helper from probe(). This was added earlier because dw_pcie_ep_init() was
> doing DBI access, which is not done now.
> 
> While at it, let's also call dw_pcie_ep_deinit() in err path to deinit the
> EP controller in the case of failure.

Is this v6.11 material?  If so, we need a little more justification
than "no need to enable".

> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> ---
>  drivers/pci/controller/dwc/pcie-qcom-ep.c | 14 ++++----------
>  1 file changed, 4 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
> index 236229f66c80..2319ff2ae9f6 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
> @@ -846,21 +846,15 @@ static int qcom_pcie_ep_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> -	ret = qcom_pcie_enable_resources(pcie_ep);
> -	if (ret) {
> -		dev_err(dev, "Failed to enable resources: %d\n", ret);
> -		return ret;
> -	}
> -
>  	ret = dw_pcie_ep_init(&pcie_ep->pci.ep);
>  	if (ret) {
>  		dev_err(dev, "Failed to initialize endpoint: %d\n", ret);
> -		goto err_disable_resources;
> +		return ret;
>  	}
>  
>  	ret = qcom_pcie_ep_enable_irq_resources(pdev, pcie_ep);
>  	if (ret)
> -		goto err_disable_resources;
> +		goto err_ep_deinit;
>  
>  	name = devm_kasprintf(dev, GFP_KERNEL, "%pOFP", dev->of_node);
>  	if (!name) {
> @@ -877,8 +871,8 @@ static int qcom_pcie_ep_probe(struct platform_device *pdev)
>  	disable_irq(pcie_ep->global_irq);
>  	disable_irq(pcie_ep->perst_irq);
>  
> -err_disable_resources:
> -	qcom_pcie_disable_resources(pcie_ep);
> +err_ep_deinit:
> +	dw_pcie_ep_deinit(&pcie_ep->pci.ep);
>  
>  	return ret;
>  }
> -- 
> 2.25.1
>